The present invention is directed toward new transition metal compounds containing bidentate E-phenoxide ligands and formal neutral ligands that are useful for the oligomerization and polymerization of olefins. Bidentate E-phenoxide ligands form 6-membered metallacycle rings when bound to a transition metal. These compounds, and optionally an activator, can be used to oligomerize or polymerize unsaturated monomers such as olefins.
Other polymerization catalysts employing bidentate ligands based on phenoxide that form six-membered metallacycle rings have been reported in the art. Mitsui has reported low activity transition metal complexes containing azo-phenoxide ligands (European Patent EP-A1 0 990 664). Low activity, low molecular weight catalysts that use an azo-phenoxide ligand based upon a naphthyl ring have also been reported in the literature (Macromolecules, 2002, 35, 6071). Catalysts based upon keto-amide structures have been reported by Dupont (WO 98/30609). These show poor activity and low molecular weight or poor molecular weight control. Imine-phenoxide catalysts based on nickel have been reported both by Grubbs (Science 2000, 287, 460; Organometallics 1998, 17, 3149; J. Pol. Sci. A. 2002, 40, 2842; WO 98/42665; WO 2000/56786; WO 2000/56787; WO 2000/56781) and Dupont researchers (WO 98/30609). These imine-phenoxide systems were examined alongside the azo-phenoxide catalysts reported here and the imine-phenoxide systems were shown to give lower molecular weight polymer.
Other references of interest include:
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